Pump

ABSTRACT

An inner rotor (a drive side) includes a plurality of slots. An outer rotor (a driven side) includes a plurality of pendulum retaining grooves. Each of pendulums includes a head section swingably fitted into a corresponding one of the pendulum retaining grooves and a body section slidably fitted into the corresponding one of the slots. A torque transmission surface of the body section includes a straight line section and a curved section. At a reference angle position at which a perpendicular line orthogonal to an eccentric direction becomes parallel to the corresponding one of the slots, the straight line section makes a surface contact on a torque-transmission-side side surface to start a torque transmission. Until a torque transmission end point, the curved section contacts on opening edge of the corresponding one of the slots. A curved section profile is set to make mutually equal angular velocities between the two rotors.

FIELD OF THE INVENTION

The present invention relates to an improvement in a rotary displacementpump, viz., so-called, a pendulum slider pump, including an inner rotor,which is connected to an outer rotor via a plurality of pendulums (orcalled linkage plates), the outer rotor and the inner rotor beingintegrally rotated with the pendulums in a mutually eccentricrelationship therebetween and the plurality of pendulums partitioning aspace formed between the outer rotor and the inner rotor into aplurality of chambers.

BACKGROUND OF THE INVENTION

Each of a Japanese Patent No. 4909078 issued on Jan. 20, 2012 and aJapanese Patent Application Publication No. 2015-117695 published onJun. 25, 2015 exemplifies a previously proposed rotary displacement pumpcalled a pendulum slider pump. Such a pendulum slider pump as describedabove includes an inner rotor which is integrally rotated with a driveshaft and an outer rotor which is rotated within a cam ring inassociation with the rotation of the inner rotor. In addition, aplurality of pendulums (linkage plates) are disposed between the outerrotor and the inner rotor in order to transmit a rotational force fromthe inner rotor at an inner peripheral side to the outer rotor at anouter peripheral side. In details, each of the pendulums (linkageplates) includes: a head section at one end fitted slidably into a plateretaining groove which corresponds to an inner peripheral surface of theouter rotor; and a body section of a substantially triangular shapefitted slidably into a corresponding one of slots radially formed on theinner rotor. These plurality of pendulums link the outer rotor and theinner rotor and partition a space defined by the outer rotor and theinner rotor into a plurality of chambers. The outer rotor is locatedeccentrically with respect to the inner rotor. Hence, the pendulumslider pump described above obtains a pump action similar to a vanepump.

It should be noted that, as one aspect of this conventional pendulumslider pump, conversely, it is possible to structure the pendulum sliderpump with the outer rotor as a drive side and the inner rotor as adriven side.

SUMMARY OF THE INVENTION

In each of the previously proposed pendulum slider pumps describedabove, basically, a transmission of a rotational torque is carried outthrough one of the plurality of pendulums. For example, in a case wherethe inner rotor is a drive side, one of the plurality of pendulumslocated at a discharge stroke side (namely, a side at which a volume ofthe chambers is decreased in association with the rotation) serves toperform the torque transmission, at least, during an angle into which360° is equally divided. Since, during this torque transmissioninterval, a distance between the outer rotor and the inner rotor whichare mutually in the eccentric relationship becomes gradually small, acorresponding one of the pendulums is moved backwardly into thecorresponding one of the slots while varying the angle with respect tothe corresponding one of the slots, acting as a kind of levertransmitting a force received from the head section to the outer rotor.

In such an operating principle as described above, during the torquetransmission interval of the corresponding one of the pendulums, arotational angle difference between the inner rotor and the outer rotoroccurs. For example, in a pendulum slider pump with the inner rotor asthe drive side, an angular velocity of the outer rotor is varied in anincrease direction and in a decrease direction while the inner rotormakes one rotation at a constant angular velocity. Specifically, avariation of the angular velocity in the increase and the decreasedirections occurs by a number of times equal to the number of thependulums.

Consequently, a ripple occurs in a discharged fluid. In the same way, aload acted upon a driving source is periodically varied. In thisrespect, an unfavorable situation occurs. The previously proposedpendulum slider pump described in the Japanese Patent No. 4909078 listsup the reduction of the ripple in the discharged fluid as one of thetasks to be solved. However, this Japanese Patent does not disclose aspecific means for making the angular velocity of the outer rotor whichserves as the driven side constant.

Even in the other pendulum slider pump in which the outer rotor is thedrive side, the variation of an angular velocity of the inner rotorwhich serves as the driven side in the increase and the decreasedirections occurs similarly.

It is an object of the present invention to provide an improved pumpwhich is capable of suppressing the ripple of discharged fluid and theperiodical load variation acted upon the driving source by rotating theinner rotor and the outer rotor at mutually equal angular speeds.

According to one aspect of the present invention, there is provided apump comprising: a cylindrical outer rotor having an inner peripheralsurface on which a plurality of pendulum retaining grooves are formed,each pendulum retaining groove being of a letter C shape in crosssection and being extended in an axial direction of the pump; an innerrotor disposed at an inner peripheral side of the outer rotoreccentrically to the outer rotor and having a plurality of slots formedon an outer peripheral surface of the inner rotor in a radial directionof the pump; and a plurality of pendulums, each pendulum having: a headsection of a substantially circular shape in cross section slidablyfitted into a corresponding one of the pendulum retaining grooves; and abody section of a substantially triangular shape in cross sectionconnected to the head section via a neck section and slidably fittedinto a corresponding one of the slots while contacting on side surfacesof both sides of the corresponding one of the slots and partitioning aspace between the outer rotor and the inner rotor into a plurality ofchambers, either of the outer rotor or the inner rotor beingrotationally driven, wherein each of the pendulums has a torquetransmission surface formed on one side surface of the body sectionopposed against a torque-transmission-side side surface of acorresponding one of the slots, the torque transmission surface having aprofile such that a straight line section and a curved section extendedfrom one end of an outer peripheral side of the straight line section toa side portion of the neck section are continued, the straight linesection has a profile such that the straight line section makes asurface contact on the torque-transmission-side side surface of thecorresponding one of the slots, at a reference angle position at which aperpendicular line orthogonal to an eccentric direction of the innerrotor and passing through a center of the inner rotor and thetorque-transmission-side side surface of the corresponding one of theslots are made parallel to each other, and the curved section has aprofile such that, at least, during a predetermined torque transmissionangle including an angle into which 360° is equally divided by thenumber of pendulums, the curved section continues the contact on anopening edge of the torque-transmission-side side surface of thecorresponding one of the slots and maintains rotational angles of bothof the rotors mutually equally.

In a specific one aspect of the present invention, the inner rotor isrotationally driven, the outer rotor is driven, and the curved sectionis extended from the straight line section toward a reverse direction to(or a rear side of) a rotation direction of the inner rotor and thereference angle position is a point at which the torque transmission isstarted.

That is, at the reference angle position at which one of side surfacesof a corresponding one of the slots corresponding to a certain singlependulum parallel to the above-described perpendicular line, thestraight line section of the torque transmission surface of the bodysection of the corresponding one of the pendulums is surface contactedon one of the side surfaces of the corresponding one of the slots at thetorque transmission side and the torque transmission with thecorresponding one of the pendulums as a kind of lever is started. Acontact point between the torque transmission surface of the bodysection and one of the side surfaces which is an opposite side of thecorresponding one of the slots is “a point of application of a force”, acontact point between the other side surface of the body section and theother side surface of the corresponding one of the slots is “a fulcrum”,and a contact point between the head section and the pendulum retaininggroove is “a point of action”. Since the point of application of forceis located at an outer peripheral end of the contact surface in a statein which the surface contact is made at the reference angle position,the point of application of force is located at the outer peripheralside with respect to the fulcrum and accordingly the torque transmissionto the outer rotor is carried out and in association with the action oflever.

Since, at an angle position before the reference angle position, an endsection (a terminal) at the inner peripheral side of the body section iscontacted on the side surface at the torque transmission side of thecorresponding one of the slots, the point of application of force islocated at the inner peripheral side and, hence, the torque cannot betransmitted under this situation.

Then, when the inner rotor is rotated starting from the reference angleposition, the curved section of the torque transmission surface iscontacted on the opening edge at the torque transmission side of thecorresponding one of the slots and the rotational torque transmission iscarried out with this contact point as the point of application offorce. Thereafter, this contact point gradually moved toward the outerperipheral side of the curved section (in other words, the tip side). Inother words, while the contact point at the curved section is graduallymoved toward the outer peripheral side, the transmission of therotational torque is continued. At this time, the rotational angle ofthe outer rotor when the inner rotor which is the drive side is rotatedin a unit angle is determined according to a profile (contour shape) ofthe curved section. Therefore, according to a setting of a profile ofthe curved section, the rotational angle of the inner rotor and therotational angle of the outer rotor can mutually equally be maintained.

In addition, a profile of the curved section is set in such a way that,at least, the curved section continues the opening edge at the torquetransmission side of the corresponding one of the slots during apredetermined torque transmission angle including an angle equallydividing 360° by the number of pendulums. Thus, by the plurality ofpendulums, the torque transmission over 360° is continuously carriedout.

In a case where the torque transmission angle is set exceeding the angleequally dividing 360° by the numbers of pendulums, a subsequent one ofthe pendulums reaches the reference angle position and the torquetransmission is started before the end of the torque transmissionthrough a preceding one of the pendulums. Hence, during a portion of theangle interval, two of the plurality of pendulums contributesimultaneously on the torque transmission.

In another specific aspect of the present invention, the outer rotor isrotationally driven, the inner rotor is driven, and the curved sectionis extended from the straight line section toward a reverse direction to(a rear side of) the rotation direction of the inner rotor, and thereference angle position is a point at which the torque transmission isended.

In this case, the basic structure of the profile of the torquetransmission remains the same as described above. However, the torquetransmission start point and the torque transmission end point arereversed to the above-described points.

That is, at an angle position which is front side with respect to therotation direction by a predetermined torque transmission angle from theabove-described reference angle position, the curved section(particularly, a portion of the outer peripheral side thereof) of acorresponding one of the pendulums is contacted with the opening edge ofthe corresponding one of the slots and the transmission of the rotationtorque is started. A contact point at the curved section is graduallymoved toward the inner peripheral side. Then, when the contact pointreaches the reference angle position, the straight line section of thetorque transmission surface makes the surface contact with the sidesurface at the torque transmission side of the corresponding one of theslots and the torque transmission side of the corresponding one of theslots and the torque transmission is ended. During this time interval,it is possible to mutually maintain equally with each other between therotation angle of the inner rotor and the rotation angle of the outerrotor by setting the profile of the curved section.

In another preferable aspect of the present invention, the curvedsection is projected from a virtual plane connecting an outer peripheralsurface and a terminal outer surface of the body section located at aninner peripheral side of the corresponding one of the slots.

That is, when, during a required torque transmission angle from thereference angle position, the profile of the curved section is set inorder for the two rotors to be interlocked with each other at equalangular speeds, the curved section is unnecessarily extended relativelylargely toward the side section of each pendulum. Hence, as comparedwith each of the shapes of well known pendulums, a unique shape isresulted. In many cases, the curved section is projected and extendedfrom the virtual plane.

In addition, from the similar reason, in another preferable aspect ofthe present invention, the curved section is constituted by a projectionsection projected in the side portion from a connecting section betweenthe body section and the neck section and a recessed section is disposedat a position of an inner peripheral surface of the outer rotor adjacentto each of the pendulum retaining grooves to avoid an interference ofthe outer rotor against the projection section.

Furthermore, in a still another preferable aspect of the presentinvention, the opening edge of each of the slots at the torquetransmission side of each of the slots which is contacted on the curvedsection of the corresponding one of the pendulums is rounded. Thus, alocal wear at the contact point can be suppressed.

According to the present invention, in the, so-called, pendulum sliderpump, the inner rotor and the outer rotor can be rotated at equalangular speeds. Thus, the ripple of discharged fluid and the periodicalload variation acted upon the drive source can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view representing a state in which a cover is removedfrom a pump in a first preferred embodiment according to the presentinvention.

FIG. 2 is a plan view representing an essential part of the pump shownin FIG. 1.

FIG. 3 is an enlarged explanatory view of one of a plurality of slotsand a corresponding one of a plurality of pendulums located at areference angle position.

FIG. 4 is a plan view of the pump in a second preferred embodiment inwhich a torque transmission angle θ is largely set.

FIG. 5 is a plan view representing a third preferred embodiment of thepump in which the outer rotor is a drive side.

FIG. 6 is a plan view representing an essential part of a comparableexample of the pump.

FIG. 7 is an enlarged explanatory view representing the plurality ofpendulums at the torque transmission start point in the comparableexample shown in FIG. 6.

FIG. 8 is an enlarged explanatory view representing the plurality ofpendulums at a reference angle position in the comparable example shownin FIG. 6.

FIG. 9 is an enlarged explanatory view representing one of the pluralityof pendulums at a torque transmission end point in the comparableexample shown in FIG. 6.

FIG. 10 is a characteristic diagram representing a rotational angledifference of an inner rotor and an outer rotor in the compatibleexample shown in FIG. 6.

EMBODIMENTS FOR CARRYING OUT THE INVENTION

First, a basic structure of a pendulum slider (type) pump according tothe present invention will herein be explained.

FIG. 1 shows a first preferred embodiment of a pendulum slider (type)pump used as, for example, a hydraulic pressure pump of an internalcombustion engine or a hydraulic pressure pump of an automatictransmission. The pump shown in FIG. 1 mainly includes: a hollow housing1; an annular shaped cam ring 2 housed in housing 1; a cylindricallyshaped outer rotor 3 arranged on an inner peripheral side of this camring 2; an inner rotor 4 arranged at a position of an inner peripheralside eccentric to outer rotor 3; a plurality of (for example, six)linkage plates (hereinafter, called pendulums) linking between outerrotor 3 and inner rotor 4; and a drive shaft 6 penetrated throughhousing 1 and linked to inner rotor 4.

The above-described housing 1 is divided into: a main frame (body) 11formed by a cam ring housing chamber 13 as a recessed section; and acover (not shown) enclosing an opening surface of cam ring housingchamber 13 in combination with this main body 11 as a lid. These mainbody (frame) 11 and cover are tightened together through bolts (notshown). Suction port 16 and discharge port 17 are respectively formed increscent shapes.

Cam ring 2 is swingably supported within cam ring housing chamber 13 viaa pin 14 attached onto one end of cam ring 2. Cam ring 2 is biasedtoward one of swing directions of cam ring 2 by means of a coil spring15 attached onto the other end of cam ring 2.

A control hydraulic pressure chamber 18 is defined to oppose against abiasing force of coil spring 15 between the inner peripheral surface ofcam ring housing chamber 13 and the outer peripheral surface of cam ring2. A balance of the biasing forces of coil spring 15 and controlhydraulic pressure chamber 18 determines a swing position of cam spring2 and, thus, a pump capacity. It should be noted that, since thisvariable capacity mechanism is not an essential part of the presentinvention, the detailed explanation will herein be omitted.

Outer rotor 3 is formed cylindrically and its outer peripheral surface 3a is rotatably fitted into a cylindrical supporting surface 19 of camring 2. A plurality of pendulum (or plate) retaining grooves 21 eachhaving a circular in cross section or a letter C shape in cross sectionare formed on an inner peripheral surface 3 b of outer rotor 3 at aplurality of locations, for example, six locations of outer rotor 3.Each plate (pendulum) retaining groove 21 is extended in the axialdirection of outer rotor 3 and both sides thereof are opened to endsurfaces of outer rotor 3, respectively.

Inner rotor 4 arranged at the inner peripheral side of outer rotor 3 ispositioned eccentrically with respect to a center of outer rotor 3 sothat inner rotor 4 approaches inner peripheral surface 3 b of outerrotor 3 and attached onto a drive shaft 6 so as to be rotated integrallywith drive shaft 6.

In details, in the above-described first embodiment, since inner rotor 4is the drive side and is mechanically driven according to an engineoutput and so on of the internal combustion engine. It should be notedthat, since a relative eccentricity (quantity) between inner rotor 4 andouter rotor 3 is varied in accordance with the swing position of camring 2.FIG. 1 shows a state in which the eccentricity (quantity) is a maximum.

Six rectangular slots 22 are radially formed on an outer peripheralsurface 4 a of inner rotor 4 at equal intervals of distance, the numberof slots 22 corresponding to that of plate (pendulum) retaining grooves21. In details, each of slots 22 has mutually parallel pairs of sidesurfaces 22 a, 22 b and these pairs of side surfaces 22 a, 22 b areformed along radius lines of inner rotor 4 so as to parallel to radiuslines of inner rotor 4. Each slot 22 is extended in an axial directionof inner rotor 4, both ends of each slot 22 opened to an end surface ofinner rotor 4, and both ends of each slot 22 are opened to end surfacesof inner rotor 4.

As described above, as a result such that inner rotor 4 is eccentric toinner peripheral surface 3 b of outer rotor 3, a space in a crescentshape is formed between inner rotor 4 and outer rotor 3. Then, thiscrescent shaped space is furthermore partitioned into six chambers 24with six pendulums 5. Each of above-described pendulums 5 is formed in aplate like shape having a pendulum shaped cross section approximated toa substantially triangular shape, supported swingably on each of plateretaining grooves 21.

As easily appreciated from FIG. 1, a distance between inner peripheralsurface 3 b of outer rotor 3 and outer peripheral surface 4 a of innerrotor 4 is varied in accordance with a rotational position of mutuallyeccentric outer rotor 3 and inner rotor 4 so that a volume of eachchamber 24 partitioned by means of linkage plates (pendulums 5) isvaried in an increase direction or in a decrease direction. Hence, by arotation of outer rotor 3 and inner rotor 4 in a counterclockwisedirection of FIG. 1, a pump action by which oil is supplied to dischargeport 17 from suction port 16 under pressure can be obtained.

FIG. 2 shows a detailed explanatory view of the pump in the firstembodiment shown in FIG. 1. Outer rotor 3, inner rotor 4, and pendulums5 which are main components of the pump. Each of pendulums 5 includes: ahead section 31 of a substantially circular shape in cross sectionswingably fitted into a corresponding one of plate (pendulum) retaininggrooves 21 of outer rotor 3; a body section 32 of the substantiallytriangular shape in cross section fitted slidably into a correspondingone of slots 22 of inner rotor 4; and a neck section 33 connecting headsection 31 and body section 32. Neck section 33 has a thickness smallerthan a diameter of head section 31 (a size along a peripheral directionof each rotor 3, 4) and body section 32 has a substantially triangularcross sectional shape approximated to an isosceles triangular shape inwhich a thickness of body section 32 is gradually expanded toward aterminal section 32 a of the inner peripheral side thereof from thisneck section 33. Forward and rearward (a front side or a forward side toa rotation direction ω and a rear side or a backward side to therotation direction) corner sections 32 b, 32 c are formed on respectivecurved surfaces so that these corner sections 32 b, 32 c aresubstantially contacted on side surfaces 22 a, 22 b at both sides of thecorresponding one of slots 22 even if corresponding one of pendulums 5is swung within the corresponding one of pendulums 5. Thus, it ispossible for each pendulum 5 to swing and move along the radiusdirection of inner rotor 4 with the corresponding one of slots 22 whilecontacting on side surfaces 22 a, 22 b of both sides of thecorresponding one of slots 22.

It should herein be noted that, in FIG. 2, inner rotor 4 is rotated in acounterclockwise direction as the drive side (a direction denoted by anarrow mark co in FIG. 2) and outer rotor 3 is driven in the samedirection via pendulums 5. Hence, one of side surfaces 22 b which isrelatively rear side (backward side) with respect to rotation directionw in two side surfaces 22 a, 22 b provides a side surface (this iscalled a torque-transmission-side side surface 22 b) for the torquetransmission. In each of pendulums 5, one of surfaces of each pendulum 5which is opposed against torque-transmission-side side surface 22 b of acorresponding one of slots 22 provides a torque transmission surface 35.

Hence, torque-transmission-side side surface 22 b of each of slots 22which is the drive side pushes torque transmission surface 35 alongrotation direction ω and this force is transmitted to outer rotor 3 viahead section 31. Thus, outer rotor 3 is driven.

Such a transmission of the rotational torque as described above isbasically carried out by a certain single pendulum 5 placed at aparticular angle position from among six pendulums 5.

In the structure of the pump in which inner rotor 4 is the drive side,the certain single pendulum 5 placed at a discharge stroke side (namely,a side at which the volume of each of chambers 24 is decreased inassociation with the rotation) assumes the torque transmission. In thefirst embodiment shown in FIG. 2, while one of pendulums 5 to which areference numeral of 5A is attached is rotated until a reach to aposition of one of the remaining pendulums 5 to which a referencenumeral of 5B is attached, the corresponding pendulum 5A carries out thetransmission of the rotational torque. In other words, a line M in FIG.2 denotes an angle position at which a torque transmission start pointis defined. In the embodiment of FIG. 2, line M denotes the angleposition which is the start point of the torque transmission by means ofsingle one of pendulums 5 and a line N denotes the angle position bymeans of the single one of pendulums 5 which is the end point of thetorque transmission.

It should herein be noted that straight line L denotes an eccentricdirection of a center of inner rotor 4 with respect to a center of outerrotor 3 and line M which provides the torque transmission line is aperpendicular line orthogonal to eccentric direction L of inner rotor 4passing through the center of inner rotor 4. When the angle position ofinner rotor 4 which provides this perpendicular line M to be parallel totorque-transmission-side side surface 22 b of the corresponding slot 22is defined as “a reference angule position”. When inner rotor 4 reachesthis reference angle position with respect to certain single slot 22,the torque transmission through certain single pendulum 5 in thecorresponding one of slots 22 is started. Then, in this embodiment,torque transmission angle θ is set to 60° which is an angle into which360° is equally divided by the number of pendulums 5 (six).

Then, when inner rotor 4 reaches this reference angle position, thetorque transmission is started by certain single pendulums 5 at thecorresponding one of slots 22. While inner rotor is rotated by 60° fromthe reference angle position, the torque transmission through thecorresponding one of pendulums 5 is carried out. When one of pendulums 5whose reference numerals 5A is rotated through 60°, the torquetransmission is ended. When the torque transmission through thesubsequent one of pendulums 5 whose reference numeral is attached as 5Creaches torque transmission start point M (in other words, the referenceangle position), this subsequent one of pendulums 5 (5C) continuouslycarries out the torque transmission. Thus, while inner rotor 4 and outerrotor 3 make one rotation, the torque transmission is continued withoutinterruption. It should be noted that above-described torquetransmission start point M and torque transmission end point N aredetermined by a profile of torque transmission surface 35 as will bedescribed later.

Next, the profile of torque transmission surface 35 required to make theangular velocity of outer rotor 3 constant will furthermore be explainedin more details.

FIG. 3 shows the corresponding one of slots 22 of inner rotor 4 and thecorresponding one of pendulums 5 located at the reference angle positionin an enlargement view. As shown in FIG. 3, torque transmission surface35 of each of pendulums 5 has a profile such that a straight linesection 35 a having a straight line slanted to form one side of atriangle and a curved section 35 b extended toward a side of necksection 33 (in other words, a rear (backward) side in rotation directionco) from one end of straight line section 35 a at the outer peripheralside thereof are continued. Curved section 35 b is constituted as aprojection section 36 which is projected from a connecting sectionbetween body section 32 and neck section 33 toward the side direction.

In more details, the profile of straight line section 35 a is definedsuch that straight line section 35 a makes a surface contact withtorque-transmission-side side surface 22 b of the corresponding one ofslots 22 when inner rotor 4 is placed at the reference angle position asshown in FIG. 3. In addition, when inner rotor 4 is furthermore rotatedfrom the reference angle position, the curved section 35 b has a profilesuch that curved section 35 b continues to be contacted on an openingedge 22 c of the corresponding one of slots 22 at the torquetransmission side of the corresponding one of slots 22 and the rotationangles of inner rotor 4 and outer rotor 3 are maintained in a mutuallyequal angular relationship. In order to obtain such a relationshipbetween both rotors 3 and 4 as described above, curved section 35 b issmoothly continued on one end of straight line section 35 a and acurvature of curved section 35 b is gradually increased from thisstraight line section 35 a toward a tip of the outer peripheral side ofcurved section 35 b.

It should be noted that, in the embodiment shown in FIG. 3, opening edge22 c of each of slots 22 is rounded with a radius of curvature smallerthan the radius of curvature of curved section 35 b so that the contactwith curved section 35 b provides at least partially a rolling contact.

In the structure described above, while the rotation torque istransmitted from inner rotor 4 to outer rotor 3 via each of pendulums 5,a difference between rotation angles of inner rotor 4 and outer rotor 3gives zero.

That is, as shown in FIG. 3, one of linkage plates (pendulums) 5 duringthe transmission of rotation torque functions as a kind of lever inwhich a contact point P1 between torque transmission surface 35 of bodysection 32 and torque-transmission-surface-side side surface 22 b of thecorresponding one of slots 22 is “a point of a lever to which force isapplied”, a contact point P2 between a surface opposite to body section32 (a corner section 32 b in a posture of FIG. 3) and a side surface 22a opposite to the corresponding one of slots 22 in a “fulcrum”, and acontact point P3 between head section 31 and a corresponding one ofplate (pendulum) retaining grooves 21 is “an application point”, and aforce applied from torque-transmission-side side surface 22 b of thecorresponding one of slots 22 to the point of application of force P1 istransmitted to outer rotor 3.

In a state where straight line section 35 a of torque transmissionsurface 35 makes the surface contact on torque-transmission-side sidesurface 22 b when inner rotor 4 is placed at the reference angleposition, point of application of force P1 is located on a most outerperipheral side of straight line section 35 a. Hence, as a radialdirectional position from a center of inner rotor 4, force point P1 islocated toward an outer peripheral side with respect to fulcrum P2 sothat the torque transmission to outer rotor 3 in association with thelever action is carried out.

Whereas, at an angle position which is present before the forward(front) side than the reference angle position, for example, as shown inFIG. 2 by one of pendulums 5 to which reference numeral of 5C isattached, corner section 32 c of body section 32 is contacted ontorque-transmission-side side surface 22 b of the corresponding one ofslots 22. Thus, since point of force of P1 becomes a positionalrelationship in which point of force P1 is located at more innerperipheral side with respect to point of fulcrum P2, no rotationaltorque can be transmitted to action point P3. Hence, it is not untilinner rotor 4 is rotated and reaches the reference angle position thatthe torque transmission is started.

Then, as inner rotor 4 is further rotated from the reference angleposition, curved section 35 b of torque transmission surface 35 iscontacted on opening edge 22 c of the torque transmission side of thecorresponding one of slots 22 and the rotational torque transmissionwith contact point P1 as “force application point”. Then, this contactpoint P1 is gradually moved toward the outer peripheral side (in otherwords, toward the tip side) of curved section 35 b. In other words,while contact point P1 is gradually moved toward the outer peripheralside of curved section 35 b, the transmission of the rotational torqueis continued. At this time, the rotational angle of outer rotor 3 wheninner rotor 4 which is the drive side is rotated through a unit angle isdetermined according to the profile of curved section 35 b. Hence, theprofile of curved section 35 b is set so that the rotational angle ofinner rotor 4 and the rotational angle of outer rotor 3 are mutuallyequally maintained and the rotational angular difference of both innerand outer rotors 4 and 3 can be maintained at zero.

A specific profile of curved section 35 b can be determined by plottingcontinuously contact point P1 required when, for example, each of innerrotor 4 and outer rotor 3 is rotated by an equal unit angle.

In this way, curved section 35 b required to zero the rotational angulardifference between inner rotor 4 and outer rotor 3 during torquetransmission angle θ is relatively long and is projected largely towardthe rear side (a reverse direction side) to rotational direction ω. Inthe first embodiment, curved section 35 b is constituted by a projectionsection 36 which is projected far away from neck section 33. Hence, inthe embodiment shown in FIG. 3, when a virtual plane PL connecting outerperipheral surface of head section 31 and corner section 32 c of bodysection 32 is supposed (to be present), curved section 35 b (projectionsection 36) is extended externally from this virtual plane PL. Thisshape is a peculiar (unique) shape as compared to any of well knownpendulums 5.

It should also be noted that a recessed section 37 is formed on theinner peripheral surface 3 b of outer rotor 3 which is adjacent to eachof pendulum retaining grooves 21 in order to avoid an interferencebetween projection section 36 and outer rotor 3 when the correspondingone of pendulums 5 is largely inclined.

It should also be noted that, in the embodiment shown in FIGS. 2 and 3,each slot 22 has a shape which is symmetric to the forward and backwarddirections with a radius line passing the center of inner rotor 4 as acenter. In other words, the center of a groove width of each slot 22 iscoincident with the radius line. However, according to the presentinvention, in the same way as a previously proposed pendulum slider(type) pump, each of slots 22 may slightly be offset to the forward andbackward directions with respect to the radius line. However, sidesurfaces 22 a, 22 b of each slot 22 are required to be parallel to theradius line passing through the center of inner rotor 4. Even in thestructure in which slots 22 are offset as described above, the referenceangle position is determined in the similar manner.

Next, FIG. 4 shows a second preferred embodiment of the pendulum slider(type) pump in which torque transmission angle θ is larger than theangle (60°) into which 360° is equally divided by the number ofpendulums 5. Specifically, in the first embodiment, the number ofpendulums 5 are six and 360° is equally divided into 60°. However,torque transmission angle θ in the second embodiment is set to be 65°larger than 60° in the first embodiment. However, this can be achievedby setting the profile of curved section 35 b larger than that of thefirst embodiment described above.

In such an arrangement described above, two pendulums 5 simultaneouslycarrying out the torque transmission at angular intervals of angles αand β which are initial and final angular stages of torque transmissionangle θ. Hence, a load is dispersed into two pendulums 5 and whenpendulums 5 carrying out the torque transmission are transited from oneof slots 22 to the subsequent one of slots 22, this transition of twoslots 22 becomes more smooth.

A comparative examples of the pendulum slider (type) pump will beexplained by reference to FIGS. 6 through 10. In FIG. 6, straight line Ldenotes an eccentric direction of the center of inner rotor 4 withrespect to the center of outer rotor 3 and line M denotes aperpendicular line orthogonal to eccentric direction L of inner rotor 4passing through the center of inner rotor 4.

In the first and second embodiments according to the present invention,this perpendicular line M is coincident with the torque transmissionline. However, in the comparative example, torque transmission angle θfrom torque transmission start point m to perpendicular line M ispresent in both sides of perpendicular line M. In comparative example ofFIG. 6, torque transmission angle θ is 60°. This torque transmissionangle θ is divided into a first interval θ1 from torque transmissionstart point m to perpendicular line M and a second interval θ2 fromperpendicular line M to torque transmission end point N.

Although each of pendulums 50 in the comparative example shown in FIG. 6has a different profile from each end of pendulums 5 in the each offirst and second embodiments, each of pendulums 50 includes torquetransmission surface 350 having straight line section 350 a and curvedsection 350 b.

FIG. 7 shows a relationship in the comparative example betweencorresponding one of pendulums 50 and slots 220 at torque transmissionstart point m. As shown in FIG. 7, at this time point of FIG. 7,straight line section 350 a makes the surface contact ontorque-transmission-“side side surface 220 b of the corresponding one ofslots 220. The torque transmission is started according to therelationship among “the point of application of force”, “the fulcrum”,and “point of action”.Next, FIG. 8 shows a state in which torque-transmission-side sidesurface 220 b of slot 220 in the comparative example becomes parallel toperpendicular line M, namely, FIG. 8 shows a state in which inner rotor4 has reached the reference angle position. It should be noted thatstraight line section 350 a continues to make the surface contact ontorque-transmission-side side surface 220 b of the corresponding one ofslots 220 up to this time at which inner rotor 4 reaches the referenceangle position.

That is, during the transition of first interval θ1 from the state shownin FIG. 7 to the state shown in FIG. 8, the corresponding one of slots220 is slid toward the inner peripheral side within each of slots 220.During this interval, an inclination angle of one of pendulums 50 withrespect to the radius line of inner rotor 4 is constant. Hence, since anangular velocity of inner rotor 4 and the angular velocity of outerrotor 3 cannot be made equal to each other and the rotation angulardifference is unavoidably generated. In details, the angular velocity ofouter rotor 3 is relatively large during first interval θ1.

When inner rotor 4 exceeds the reference angle position, opening edge220 c of the corresponding one of slots 220 at the torque transmissionside is contacted on curved section 350 b of torque transmission surface350 and the torque transmission is continued while moving on curvedsection 350 b. In details, during second interval of θ2, the torquetransmission is continued while the contact point moving on curvedsection 350 b. That is, during second interval θ2, the torquetransmission is carried out by curved section 350 b. FIG. 9 shows thestate of inner rotor 4 and outer rotor 3 when inner rotor 4 reachestorque transmission end point N, an end terminal of curved The endterminal at the outer peripheral side of curved section 350 b iscontacted on opening edge 220 c of the corresponding one of slots 220.It should herein be noted that the angle position of inner rotor 4 shownin FIG. 9 provides the torque transmission end point N and,simultaneously, the torque transmission of the shown pendulum 50 attorque transmission start point m for the subsequent one of pendulums50. The rotational angular difference of inner rotor 4 and outer rotor 3which is zero at torque transmission start point m shown in FIG. 7 isrequired to return to zero again at torque transmission end point Nshown in FIG. 9. Unavoidably, the profile of curved section 350 b is setto such that the angular velocity becomes relatively small.

FIG. 10 shows a characteristic of the rotational angular differencebetween inner rotor 4 and outer rotor 3 in the comparative example shownin FIGS. 6 through 9. A lateral axis of this graph denotes an angle ofinner rotor 4 and, in the shown comparative example in which inner rotor4 is the drive side, rotation direction of ω is denoted by an arrow ω. Alongitudinal axis of this graph denotes the rotational angle differenceof two rotors 3 and 4. A lower side of this graph provides a lead side(advance) side of outer rotor 3.

As shown in FIG. 10, during first interval θ1 starting from transmissionstart point m, the angular velocity of outer rotor 3 being relativelylarger and the rotation angular difference being abruptly expanded. Wheninner rotor 4 is placed at the reference angle position (the positioncorresponding to perpendicular line M), the rotational angulardifference becomes a maximum. During second interval θ2, the angularvelocity of outer rotor 3 becomes, reversely, small and, at the torquetransmission end point N at which second interval of θ2 is ended, therotational angular difference is again zeroed.

Hence, such an angular velocity variation of outer rotor 3 is generatedfor each pendulum 50 (for each of 60°) and a ripple of discharged fluidand a load variation in the drive source are introduced.

In order to prevent such a characteristic of the comparative example asdescribed above, outer rotor 3 is rotated to follow up inner rotor 4while maintaining the rotational angular difference between inner rotor4 and outer rotor 3 at zero, in the above-described embodiments. Hence,the ripple of discharged fluid and the load variation in the drivesource are suppressed.

It should be noted that the pump in the first embodiment shown in FIG. 1is constituted as a variable capacity pump in which the eccentricity(quantity) between inner rotor 4 and outer rotor 3 is varied inaccordance with the swing position of cam ring 2. In such a pump inwhich the eccentricity (quantity) as described above, the rotationalangular velocity between inner rotor 4 and outer rotor 3 becomes zero ata time of a particular eccentricity (quantity). In the shownembodiments, the rotational angular difference is set to be zero. It ispossible to set the rotational angular difference to be zero at a timeof a particular intermediate eccentricity (quantity).

It is, of course, possible to apply the present invention to a pump of afixed capacity in which the eccentricity (quantity) is fixed. Inaddition, the number of pendulums 5 is not limited to six as describedin the first embodiment. The present invention is applicable to the pumphaving an arbitrary number of pendulums 5.

Furthermore, the present invention is applicable to the pendulum slider(type) pump in which the outer rotor is the drive side and the innerrotor is driven side.

FIG. 5 shows a third preferred embodiment of the pendulum slider (type)pump in which outer rotor 300 functions as a rotor of an electric(electrically driven) motor which is directly rotationally driven. Outerrotor 300 is rotatably supported in housing 100. A plurality of, forexample, six permanent magnets 101 are buried at equal intervals intothe outer peripheral section of outer rotor 300. An annular stator core102 constituting the electric (electrically driven) motor together withouter rotor 300 includes a nine slot stator core 103 of laminated ironcores having a plurality of, for example, nine poles 103 a and coils 104wound on respective poles 103 a.

It should be noted that outer rotor 300 is rotated in thecounterclockwise direction shown by an arrow mark with ω. Accordingly,inner rotor 4 is driven and rotated in the same direction as outer rotor300 to obtain the pump action. It should be noted that, since the torqueis transmitted from torque transmission surface 35 of the correspondingone of pendulums 50 to torque-transmission-side side surface 22 b of thecorresponding one of slots 22 in the third embodiment of FIG. 5 in whichouter rotor 300 is the drive side, directions of individual pendulums 5are opposite to the rotational direction of ω.

In other words, the relationship between pendulums 5 and slots 22 in thecase of pump shown in FIG. 5 is substantially equal to the structure inwhich outer rotor 3 (300) is, reversely, rotationally driven in theclockwise direction in FIGS. 2 and 3. Then, “transmission end point N”in FIG. 2 provides the “transmission start point” and “transmission endpoint M” in FIG. 2 provides the transmission end point. Hence, from astate in which a most outer peripheral section of curved section 35 b oftorque transmission surface 35 of the corresponding one of pendulums 5is contacted on opening edge 22 c at the torque transmission side of thecorresponding one of pendulums 5, the torque transmission is started. Inaccordance with the profile of this curved section 35 b, inner rotor 4is driven while such a relationship that inner rotor 4 is rotated by anangle equal to the rotation of the unit rotational angle of outer rotor3 (300) is maintained. Then, at a time point at which side surfaces 22a, 22 b of the corresponding one of slots 22 make surface contact ontorque-transmission-side side surface 22 b of the corresponding one ofslots 22, the torque transmission is ended. At a position at which outerrotor 3 (300) is rotated further than the reference angle position(refer to one of pendulums 5 to which reference numeral of 5C isattached), the torque transmission is not possible in the same way asdescribed in the first embodiment.

Hence, even in the pump in the case of the third embodiment shown inFIG. 5, the rotational angular difference between outer rotor 300 andinner rotor 4 can be maintained at zero and the ripple of dischargedfluid and the load variation as the electric (electrically driven motor)motor can be suppressed.

It should be noted that, although, in the third embodiment shown in FIG.5, torque transmission angle θ gives 60° to which, for example, 360° isequally divided by the number of pendulums 5, it is possible to set alarger angle than 60° in the same way as the second embodiment. In thiscase, the pump is structured so that the torque transmission start pointbecomes earlier. That is, in the structure in which inner rotor 4 isdriven as shown in FIG. 5, curved section 35 b of torque transmissionsurface 35 is extended toward the forward side of rotational directionco from straight line section 35 a and by more elongating this curvedsection 35 b, the torque transmission start point can be made earlier sothat torque transmission angle θ can widely be obtained. It should benoted that it is necessary that the torque transmission end point isalways at the above-described reference angle position.

It should finally be noted that, in FIGS. 2, 4, 5, and 6, suction port16 and discharge port 17 are omitted only for explanation convenience.

This application is based on a prior Japanese Patent Application No.2016-240779 filed in Japan on Dec. 13, 2016. The entire contents of thisJapanese Patent Application No. 2016-240779 are hereby incorporated byreference. Although the invention has been described above by referenceto certain embodiments according to the invention, the invention is notlimited to the embodiments described above. Modifications and variationsof the embodiments described above will occur to those skilled in theart in the light of the above teachings. The scope of the invention isdefined with reference to the following claims.

EXPLANATIONS OF SIGNS

-   -   1 . . . housing    -   2 . . . cam ring    -   3 . . . outer rotor    -   4 . . . inner rotor    -   5 . . . pendulums    -   21 . . . pendulum retaining grooves    -   22 . . . slots    -   22 b . . . torque-transmission-side side surface    -   22 c . . . opening edge    -   31 . . . head section    -   32 . . . body section    -   33 . . . neck section    -   35 . . . torque transmission surface    -   35 a . . . straight line section    -   35 b . . . curved section

What is claimed is:
 1. A pump comprising: a cylindrical outer rotorhaving an inner peripheral surface on which a plurality of pendulumretaining grooves are formed, each pendulum retaining groove being of aletter C shape in cross section and being extended in an axial directionof the pump; an inner rotor disposed at an inner peripheral side of theouter rotor eccentrically to the outer rotor and having a plurality ofslots formed on an outer peripheral surface of the inner rotor in aradial direction of the pump; and a plurality of pendulums, eachpendulum having: a head section of a substantially circular shape incross section slidably fitted into a corresponding one of the pendulumretaining grooves; and a body section of a substantially triangularshape in cross section connected to the head section via a neck sectionand slidably fitted into a corresponding one of the slots whilecontacting on side surfaces of both sides of the corresponding one ofthe slots and partitioning a space between the outer rotor and the innerrotor into a plurality of chambers, either of the outer rotor or theinner rotor being rotationally driven, wherein each of the pendulums hasa torque transmission surface formed on one side surface of the bodysection opposed against a torque-transmission-side side surface of acorresponding one of the slots, the torque transmission surface having aprofile such that a straight line section and a curved section extendedfrom one end of an outer peripheral side of the straight line section toa side portion of the neck section are continued, the straight linesection has a profile such that the straight line section makes asurface contact on the torque-transmission-side side surface of thecorresponding one of the slots, at a reference angle position at which aperpendicular line orthogonal to an eccentric direction of the innerrotor and passing through a center of the inner rotor and thetorque-transmission-side side surface of the corresponding one of theslots are made parallel to each other, and the curved section has aprofile such that, at least, during a predetermined torque transmissionangle including an angle into which 360° is equally divided by thenumber of pendulums, the curved section continues the contact on anopening edge of the torque-transmission-side side surface of thecorresponding one of the slots and maintains rotational angles of bothof the rotors mutually equally.
 2. The pump as claimed in claim 1,wherein the inner rotor is rotationally driven, the outer rotor isdriven, and the curved section is extended from the straight linesection toward a reverse direction side to a rotation direction of theinner rotor and the reference angle position is a point at which thetorque transmission is started.
 3. The pump as claimed in claim 1,wherein the outer rotor is rotationally driven, the inner rotor isdriven, and the curved section is extended from the straight linesection toward a forward side of a rotation direction of the inner rotorand the reference angle position is a point at which the torquetransmission is ended.
 4. The pump as claimed in claim 1, wherein thecurved section is projected and extended from a virtual plane connectingan outer peripheral surface of the head section and a terminal outersurface of an inner peripheral side of the body section.
 5. The pump asclaimed in claim 1, wherein the curved section is constituted by aprojection section projected toward a side direction from a connectingsection between the body section and the neck section and a recessedsection is disposed at a position of the inner peripheral surface of theouter rotor adjacent to each of the pendulum retaining grooves to avoidan interference of the outer rotor against the projection section. 6.The pump as claimed in claim 1, wherein the opening edge at thetorque-transmission-side side surface of each of the slots which iscontacted on the curved section of the corresponding one of thependulums is rounded.